Original described as Laimosemion mabura.

Described from a small stream belonging to the Essequibo River drainage, central Guyana. Males of Rivulus mabura are similar to those of R. dibaphus, to which the new species may be closely related, in possessing bluish black pigmentation on the caudal peduncle, but differ in certain morphological characters and elements of colour pattern. The new species belongs to the R. geayi species group, and is distinguished from other members of this assemblage by male colour pattern.